My hands arent too strong but I can rack my M&P40 fs just fine. Pushing it like this person suggests is an idea as well. The rippling on the rear of the slide gave me something to grip on when id push the frame forward.

Keep in mind a new gun will be a bit stiff. When she brings it home, clean/lube it and rack it a bunch to help loosen it a bit. Bunch of rounds down range should help.